Rapid expansion of the distributional range and the population genetic structure of the freshwater amphipod Crangonyx floridanus in Japan

Asako Nagakubo, Kazuki Sekiné, Yoshiki Tanaka, Ryoichi B. Kuranishi, Shoji Kanada, Koji Tojo
2010 Limnology  
The freshwater amphipod Crangonyx floridanus (Amphipoda: Crangonyctidae) has considered to be recently introduced from North America to Japan, and now the recorded sites of collection cover nearly all over Japan excluding the northern part. In this study, we surveyed further areas outside the known distribution ranges and also examined the population genetic structure and the phylogenetic relationships between Japanese and North American populations based on nuclear (18S rRNA) and mitochondrial
more » ... (COI) DNA sequences. We found that this amphipod already reached to Hokkaido, the northernmost Japan, and suggested the rapid expansion in a pattern of concentric circles from the central part of Japan. The genetic analysis showed the genetic homogeneity of Japanese population in contrast to the genetic diversification in North American Crangonyx populations. The process of introduction, establishment, and expansion of this amphipod in Japan may be explained as follows. A limited number of individuals from a North American native population were probably inadvertently introduced and established somewhere within the Kanto region. After that the local population size increased and the range of its distribution was rapidly expanded over Japan.
doi:10.1007/s10201-010-0323-3 fatcat:kizgjt7pijhbpavsichqdsxykq